Effect of Growth regulators, Sucrose and Glutamine on Shoot Regeneration from Node Derived Callus Cultures of Rubber yielding species - Parthenium argentatum

The nodal explants of guayule (Parthenium argentatum Gray) when cultured on Murashige and Skoog's (MS) medium fortified with different concentrations of kinetin (KN), 6benzylaminopurine (BAP), 2,4dichlorophenoxyacetic acid (2,4-D), 2,4-D + BAP, napthaleneacetic acid (NAA) and NAA + BAP produced callus tissues and few shoots. The percent frequency of callus was around 90% with

0.5 mg/l BAP and NAA. The high frequency shoot regeneration from the node derived callus of guayule was observed when MS medium was supplemented with BAP, NAA + BAP with varying concentrations of sucrose. Sucrose at 34% levels increased the number of shoots formed (12–15) per 250 mg of callus. Glutamine at 200 mg/l level further enhanced the number of shoots formed (22–25) per callus mass. The percent frequency of shoot regeneration from callus tissues was high (88%) when the medium was fortified with 0.1 mg/l NAA + 2.5 mg/l BAP, 200 mg/l glutamine and 2% sucrose. The ability of the callus tissues of guayule remained more or less same for shoot regeneration over a period of 200 days; but decreased thereafter. Shoots rooted with 15 to 75% frequency and the whole plants when transferred to pots survived with 60% frequency.